The invention covers the field of cellular mobile telephones. It relates to a test facility and a method for its operation for the permanent monitoring of the services provided by a GSM network (Global System for Mobile Communication). In particular checks are made whether the services subscribed to by a user in his/her home network or at his/her home location are also available in the visited network or location respectively. Apart from these so-called roaming tests it is also of interest as to with what quality the services offered in the GSM network are available. Because the network functions and services should be tested in the same way as a customer actually uses them, they logically have to be tested from the customer network interfaces. The customer network interfaces at the air interface are of particular importance, i.e. to the mobile station (MS), and at the switched network for conventional analogue and ISDN telephone services (Integrated Services Digital Network). However, for special tests internal interfaces of the GSM network are also of significance such as the so-called A-Interface at the MSC (Mobile Switching Center).
Mobile communication networks such as the GSM (Global System for Mobile Communication) are experiencing increasing customer numbers due to good availability, fast connection capabilities and worldwide ability for contact under the same number. To ensure that such a highly complex system functions efficiently and reliably under varied peripheral conditions, a series of measures is necessary. One of these measures is the almost continuously conducted testing of the various functions of networks and the services provided which are subject to constant modifications, especially expansions. Since a radio transfer is exposed to substantially greater interference effects overall than a transfer by cable, the testing of the so-called air interface, i.e. the radio link between the mobile customer terminal, the mobile station (MS), often just called Handy, and the so-called base station, i.e. the sending/receiving station at a fixed location, is therefore on one hand especially important. On the other hand the number of interfaces is also increasing rapidly at other locations, as explained below, so that it can be useful to include these in tests if reliable results are to be obtained.
For testing the air interface within a mobile communication network the use of automated test facilities for alternate routing and toll billing, is already known. Such a facility and the appropriate operating method are described in German patent document DE 196 20 164. The test facility described in this document consists essentially of a special mobile station (MS), also known as Handy, which is equipped with a wire-bound interface, a multiplexor to hold and alternately operate several data modules, i.e. SIMs (Subscriber identity Modules), and a computer which controls the whole facility. Instead of a SIM the MS contains an adapter module which is connected to the multiplexor via cable in such a way that each of the SIMs contained in the multiplexor is emulated in the MS. The selection of the respectively required SIM and the control of the entire test process are performed by the control computer which has to be connected to the MS and to the multiplexor for this purpose.
Undoubtedly the facility described in DE 196 20 164 already permits an automated test of alternate routing and toll billing. The disadvantage however is that a multitude of multiplexors have to be placed at different locations in order to conduct tests that extend across an entire network and, if necessary, several countries. Such extended tests have today become indispensable because of the continuously increasing roaming possibilities. Roaming is the use of an MS outside the home network in which it is registered and in whose data banks its data is stored.
In addition the focus on testing of the air interfaces alone is no longer sufficient because the number of other gateways is also increasing. As a result of the steadily increasing number of network operators to which deregulation in many countries is contributing, the number of gateways between mobile communication networks on the one hand is growing as well as the number of network gateways to switched networks and between these networks. Therefore it is appropriate and necessary to also include switched network gateways in the tests.
This is connected to the fact that a SIM is required in all network accesses which are to be tested, for the international and national roaming test from each network or from each location within a network respectively. The configuration with distributed SIMs demands a substantial effort with regard to establishing the configuration. On one hand the number of roaming agreements grows with the increase in mobile communication networks, on the other hand, with the increase in customers, the number of MSC (Mobile Switching Center) and therefore the locations within the network necessarily rise. In order to guarantee the total availability of the services for network subscribers and roaming customers at any time tests have to be performed with each SIM at each location which in turn requires a large number of SIMs at each location. The expansion of the networks, usually nationally if not internationally, makes the maintenance of these extensive sets of locally distributed SIMs more difficult and requires substantial effort in terms of material and time.
It is therefore the task of the invention to establish a test facility and a test method which is capable of solving the problems outlined. For this, it should be possible to perform tests efficiently for already existing data networks as centrally as possible from a single location. In other words, it will be possible to use the invention immediately without any change or extension to existing mobile communication networks. It will furthermore be adaptable in the respect that it can be adapted to network changes or expansions using a simple modification, preferably of the software, at a central location when the roaming agreements as well as the number of customers and the resulting increase in Home Location Register (HLR) grow which require a change of one or more tests or parts thereof.
These tasks are solved in principle by the fact that according to the invention at least one central server is provided which can adopt a multitude of SIMs, and that a large number of geographically distributed mobile stations equipped with adapter modules or mobile stations simulated by software processes can access this central server via at least one existing data network so that each SIM can be emulated in each of the distributed mobile stations. Further forms of the invention can be derived from the instant disclosure and, details can be collected from the following description.
The test facility according to the invention not only makes it possible to continuously monitor the availability of the services provided, but also to alter these tests constantly and, whenever necessary, to adapt them to the growing demands efficiently. In particular the following tests should be performed or the following services should be tested respectively:
Basic Services, i.e. the basic services which are available to every customer
Supplementary Services, i.e. the supplementary services such as call forwarding, call suspending
Data and fax services, i.e. non-linguistic services that can process many MS
Toll estimation, i.e. the toll billing, calculation and, if necessary, display
International Roaming, i.e. the trunking scheme outside the home country
National Roaming, i.e. the trunking scheme outside the location in which the relevant SIM is registered.